This invention relates generally to systems and devices for use in the infusion of medical liquids into a patient. More particularly, this invention relates to an improved fluid infusion system for controlled and selected administration of a primary infusion fluid and a secondary infusion fluid to a patient.
A variety of medical liquids are commonly administered intravascularly to a patient in the course of medical treatment. Such medical liquids can include, for example, saline or dextrose solutions or other fluids for correcting body chemistry imbalances or medical solutions prescribed for treatment of disease. These medical liquids are normally available commercially in aseptic containers having self-sealing caps of a resilient material adapted to be punctured by an appropriate instrument, such as a hypodermic needle for removing the fluid contents for supply to the patient.
Infusion of medical liquids is normally carried out by use of a so-called intravenous administration set, sometimes referred to as an IV set, which includes means for puncturing the self-sealing cap of the fluid container and means for guiding the fluid in a continuous regulated flow to a catheter or the like inserted, for example, into the vein of a patient. Such IV sets typically include a drop former having a spiked conduit at one end for insertion into the fluid container which is normally supported in an inverted position above the patient. The drop former converts fluid flowing from the container into a progression of drops which fall through a transparent drop chamber for visual observation by medical personnel or detection by appropriate electronic instrumentation to confirm the presence and rate of fluid flow. The drops collect within a lower region of the drug chamber for flow into a flexible and normally transparent length of plastic tubing connected in turn to the intravenous catheter. Flow rate control devices, such as a manually adjustable roller clamp or automated flow control instrument, are provided along the length of the plastic tube to control the rate of fluid delivery to the patient.
In many instances, during infusion of a medical liquid into a patient, it is necessary or desirable to administer a prescribed quantity of a different or second medical fluid. For example, during infusion of a saline or dextrose solution, it may be necessary to administer a small quantity of a selected drug solution to the patient. This second medical fluid can be administered via a separate intravenous access site by use of a hypodermic syringe or an additional IV set, but such techniques undesirably require additional needle punctures in the patient to increase patient trauma, both physically and emotionally. Accordingly, it has generally been desirable to administer such additional medical fluids through the plastic tubing and catheter of the in situ IV set.
To accommodate occasional administration of a secondary infusion fluid, modern IV sets commonly include a so-called Y-site fitting installed along the length of the plastic fluid flow tubing. The Y-site fitting comprises a primary conduit connected in-line with the plastic tubing for normal passage of the primary infusion supplied to the patient, in combination with a short branch conduit having a free end closed by a self-sealing resilient cap. According to conventional techniques, the secondary infusion fluid can be injected through the self-sealing cap of the Y-site fitting by use of a hypodermic syringe, but such techniques are not particularly well suited for infusing the secondary fluid over a prolonged time period. Alternatively, the secondary infusion fluid can be injected into the Y-site fitting through a hollow needle which in turn is connected through an auxiliary IV set to a secondary fluid container suspended typically for gravitational flow at a height greater than the primary fluid container. This latter technique, however, incorporates a number of significant disadvantages, including, for example the requirement of a relatively high degree of attention and manipulation by medical personnel, together with increased costs associated with the use of an auxiliary IV set and specially adapted primary IV sets including a check valve to prevent inadvertent backflow of the secondary fluid into the primary fluid container.
A number of other fluid infusion systems and devices have been proposed in attempts to accommodate facilitated and cost-effective introduction of a secondary infusion fluid into an in situ IV set. These system proposals generally envision specialized adapter fittings in-line with the plastic tubing of the IV set wherein a secondary fluid container can be connected when desired to the adapter fitting to supply the secondary fluid through the tubing to the patient. In general, however, these proposed systems have been relatively complex in construction and have required a number of manipulative steps including halting of primary fluid flow preparatory to administration of the secondary infusion fluid. These manipulative steps require considerable skill of medical personnel and further must be performed hurriedly to prevent activation of alarm devices sensing the absence of fluid flow through the drop former device of the IV set. Accordingly, these proposed infusion systems generally have not achieved any significant degree of consumer acceptance.
There exists, therefore, a significant need for an improved fluid infusion system including relatively simple, inexpensive, easy-to-use, and preferably disposable apparatus facilitating occasional interruption of primary infusion fluid administration to permit infusion of a selected secondary fluid followed by automatic resumption of primary fluid flow. The present invention fulfills these needs and provides further related advantages.